If pulmonary edema has been developing gradually, symptoms of fluid overload may be elicited. These include nocturia (frequent urination at night), ankle edema (swelling of the legs, generally of the "pitting" variety, where the skin is slow to return to normal when pressed upon), orthopnea (inability to lie down flat due to breathlessness) and paroxysmal nocturnal dyspnea (episodes of severe sudden breathlessness at night).

Pulmonary edema is generally suspected due to findings in the medical history, such as previous cardiovascular disease, and physical examination: end-inspiratory crackles (sounds heard at the end of a deep breath) on auscultation (listening to the breathing through a stethoscope) are characteristic for pulmonary edema. The presence of a third heart sound (S3) is predictive of cardiogenic pulmonary edema.[१]

The diagnosis is confirmed on X-ray of the lungs, which shows increased fluid in the alveolar walls. Kerley B lines, increased vascular filling, pleural effusions, upper lobe diversion (increased blood flow to the higher parts of the lung) may be indicative of cardiogenic pulmonary edema, while patchy alveolar infiltrates with air bronchograms are more indicative of noncardiogenic edema[१]

Low oxygen saturation and disturbed arterial blood gas readings may strengthen the diagnosis and provide grounds for various forms of treatment. If urgent echocardiography is available, this may strengthen the diagnosis, as well as identify valvular heart disease. In rare occasions, insertion of a Swan-Ganz catheter may be required to distinguish between the two main forms of pulmonary edema.[१]

When circulatory causes have led to pulmonary edema, treatment with intravenous nitrates (glyceryl trinitrate), and loop diuretics, such as furosemide or bumetanide, is the mainstay of therapy. These improve both preload and afterload, and aid in improving cardiac function.

There are no causal therapies for direct tissue damage; removal of the causes (e.g. treating an infection) is the most important measure.